Saikin, Imouto no Yousu ga Chotto Okashiinda ga. OVA

(Esta sinopse está em inglês. Ajude a comunidade traduzindo!)

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This OVA is divided into two parts. First one is about Torii Shoutarou following his younger sister on a date. Second one is about Christmas Eve, which Mitsuki, Yuuya and their friends spend at Kanzaki's house.

Bundled with the limited-edition volume 7 of the manga.

(Source: AniDB)